In Final Cut Pro, you can arrange its windows any number of ways, allowing you to choose a configuration that best suits your needs. If you have more than one display connected to your computer, you can arrange Final Cut Pro windows across multiple displays.
However, in Final Cut Pro 5 it may seem difficult to get the Timeline to span the displays—when you try to resize the Timeline across the displays the common way, by dragging the window's lower-right corner, it may snap to conform to the edges of only one display.
Instead, try dragging the edges of the window to resize it rather than dragging the lower-right corner. You can reposition the entire window by dragging from the title bar, and then resize it by dragging its edges, not its corner.
This document will be updated as more information becomes available.